In cellular mobile communication networks, simultaneous transmission over air interfaces using the same physical resources frequently occurs. Thereby, co-channel interference is caused which reduces the signal quality of transmission signals. This in turn reduces the transmission capacity of the mobile communication network. Co-channel interference becomes even more critical in mobile communication networks having a dense deployment of access nodes.
Cooperation of access nodes is a possibility to increase the signal quality of transmission signals and the transmission capacity of a mobile communication network. For access node cooperation, an initial communication between an access node (a so called “serving access node”) and a mobile station is extended in that the mobile station additionally communicates via at least one further access node (a so called “supporting access node”). Thereby, the serving access node additionally uses the transmission and receiving capacities of the at least one supporting access node for communicating with the mobile station. For using the additional transmission and receiving capacities, user data, control data and data for operation and maintenance (O&M) has to be exchanged between the serving access node and the at least one supporting access node (e.g., via a core network).
However, the transport links connecting the serving access node and the at least one supporting access node may not have sufficient transport link capacity for transmitting the required user data, control data and data for O&M between the serving access node and the at least one supporting access node. In case of distant access nodes, the transport link can, for example, be realized as a leased wired telephone line having a transport link capacity of about 2 Mbps, a wireless microwave link having a transport capacity of several tens of Mbps, a wired Digital Subscriber Line (DSL) connection having a transport capacity of several hundreds of Mbps, or a wired fibre connection having a transport capacity of several thousands of Mbps. In case of co-located access nodes, the transport link might, for example, be a computer bus running on the backplane of a server rack connecting two processing units. Due to the limited bandwidth of such or similar transport links, sometimes not sufficient user data, control data and data for O&M can be transported between the serving access node and the at least one supporting access node so that the access nodes cannot cooperate with each other.
Thus, for access nodes cooperating or intending to cooperate with each other in order to serve at least one mobile station, the problem of limited transport link capacity on the network path between the access nodes arises.